This renewal requests support for years 25-30 to extend studies on drug development within the framework of glutathione (GSH), glutathione S-transferases (GST) and pathways that maintain thiol homeostasis. Attachment of GS- to acceptor cysteine residues (glutathionylation) is becoming recognized as a post-translational modification that can alter the structure and function of proteins in a significant manner. We have found that a novel glutathione S-transferase (GST) activated pro-drug (PABA/NO) releases nitric oxide, inducing cytotoxicity and causing glutathionylation of a number of cellular proteins. We wish to identify these and determine their relevance to the drug's mechanism of action. Extending our goal to develop new cancer drugs, we have included approaches that will assist in pre-clinical development of PABA/NO and of a platinum stabilized form of oxidized glutathione (NOV-002). These will include in vitro and rodent studies, particularly for determination of mechanism of action and pharmacokinetics. Drug resistant cell lines will be created and subject to gene expression studies using our amplified differential gene expression microarray technology (ADGE-microarray). Data from these lines will be used to confirm and extend drug target identification and validation. GST and other thiol based cell constituents (such as thioredoxin) play a leading role in regulating critical kinase signaling molecules. We will clone and characterize mammalian sulfiredoxin, a gene that has, until now, only been identified in yeast. What role this protein has in intracellular redox cycling and the regulation of drug response and signaling pathways will be the topic of one aim. Extension of our GST/JNK work will include large-scale purification and crystallization of the complex and will seek to extend the observation that bone marrow cells from GSTrc null mice have enhanced proliferation rates associated with altered expression of JAK- STAT and certain cellular phosphatases (SHP-1 and -2). We will attempt to solidify this connection as a means of consolidating these pathways. Overall, we seek to enhance the collective appreciation of the importance of GSH/GST and associated pathways in controlling cellular homeostasis and develop drugs that target these pathways.